diff options
| author |   Peter Zijlstra <peterz@infradead.org> | 2019-10-30 20:30:41 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2020-02-11 13:10:56 +0100 |
| commit | 7f26482a872c36b2ee87ea95b9dcd96e3d5805df (patch) | |
| tree | 0a0e843a50333cc34780860e3378ecae2c5a52bf /include/linux/wait.h | |
| parent | locking/percpu-rwsem: Extract __percpu_down_read_trylock() (diff) | |
| download | linux-dev-7f26482a872c36b2ee87ea95b9dcd96e3d5805df.tar.xz linux-dev-7f26482a872c36b2ee87ea95b9dcd96e3d5805df.zip | |
locking/percpu-rwsem: Remove the embedded rwsem
The filesystem freezer uses percpu-rwsem in a way that is effectively
write_non_owner() and achieves this with a few horrible hacks that
rely on the rwsem (!percpu) implementation.
When PREEMPT_RT replaces the rwsem implementation with a PI aware
variant this comes apart.
Remove the embedded rwsem and implement it using a waitqueue and an
atomic_t.
- make readers_block an atomic, and use it, with the waitqueue
for a blocking test-and-set write-side.
- have the read-side wait for the 'lock' state to clear.
Have the waiters use FIFO queueing and mark them (reader/writer) with
a new WQ_FLAG. Use a custom wake_function to wake either a single
writer or all readers until a writer.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200204092403.GB14879@hirez.programming.kicks-ass.net
Diffstat (limited to 'include/linux/wait.h')
| -rw-r--r-- | include/linux/wait.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h index 3283c8d02137..feeb6be5cad6 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -20,6 +20,7 @@ int default_wake_function(struct wait_queue_entry *wq_entry, unsigned mode, int #define WQ_FLAG_EXCLUSIVE 0x01 #define WQ_FLAG_WOKEN 0x02 #define WQ_FLAG_BOOKMARK 0x04 +#define WQ_FLAG_CUSTOM 0x08 /* * A single wait-queue entry structure: |